Charging device for a furnace

ABSTRACT

A blast furnace charging device having a distributing hopper vertically movable above a small charging bell and a large charging bell below the small bell, with the hopper resting on a protective element on the outside of the small bell which acts as a mobile base for the hopper, and the device charging the furnace by successive vertical movements of the hopper and small bell, and the large bell.

United States Patent Inventors Appl. No.

Filed Patented Assignee Priority Leon Jean Barballe Seraing; Maurice Joseph Hermans, Liege, Belgiu 714,668 7 Mar. 20, 1968 Jan 12, 1971 Centre Natiouale De Recherches Metallurgiques Brussels, Belgium in company of Belgium Mar. 20, 1967 Luxembourg CHARGING DEVICE FOR A FURNACE 7 Claims, 2 Drawing Figs.

US. Cl 214/37, 266/27 Int. Cl B66c 17/08 Field of Search 266/27; 214/36, 37

References Cited UNITED STATES PATENTS 4/1889 Walsh 214/36 l0/ 1 940 Koppers 214/36 5/1965 Tsujihata et al. 266/27 5/1966 lsaacs 266/27X 9/1966 Hanna 266/27 2/1967 Tsutsumi 266/ 27X Primary Examiner-J. Spencer Overholser Assistant Examiner-John E. Roethel Attorney-Holman, Glascock, Downing & Seebold ABSTRACT: A blast furnace charging device having a dis tributing hopper vertically movable above a small charging bell and a large charging bell below the small bell, with the hopperresting on a protective element on the outside of the small bell which acts as a mobile base for the hopper, and the device charging the furnace by successive vertical movements of the hopper and small bell, and the large bell.

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The invention relates to a charging device for a shaft furnace, more particularly for use with a blast furnace operating with or without high top pressure, where it isintended to provide a gastight closure.

Shaft furnaces and in particular blast furn'aces are known to be provided at the top with a charging device consisting for example of a skip or conveyor belt dumpingthe materials for charging, i.e. ore, flux and coke into a distributing device intended to ensure maximum homogeneity of each component of .the charge and optimum distribution of the charge in the furnace, while preventing any direct connection between the inside of the furnace and the outside atmosphere. I

A frequently used distributing device for this operation consists of a hopper open at the top and twobells, the smaller of which, situated at the bottom of the hopper, serves as a hopper A base while the larger, situated below the smaller bell, controls the dumping of the "charge into the furnace. Generally the hopper into which the charge is deposited by the charging device'is rotatably mounted and provided with a control device to rotate it as required. The small bell forming the base of this hopper is rotated by friction when the hopper rotates.

, The facility of rotating the distributing hopper gives rise to difficulties in making the charging device gastight, particularly A second sealis arranged between the hopper and the small .bell acting as its base. This seal is subjected to gradual wear (with lossof gastightness) as a result of both abrasion by the charge dropping on the sealsand'the relative rotation of the hopper and the small bell which: is pressed against it and moved by friction:

Also, since the large bell'is nohrotatable and the small bell can rotate, it 'is'necessary to have an additional seal separating the coaxial elements supporting the two bells.

furnaces, so that a number of the accessories already on the furnace can be retained.

The invention consists in a charging device for a shaft furnace comprising a distributing hopper for receiving a furnace charge through charging means such as a receiving hopper, a large bell, a small bell, means suspending said bells with the small bell above the large bell and means defining a chamber between the two bells. The distributing hopper istprovided with a device enabling it to slide along its longitudinal axis and with a rotating device, and the small bell is provided with a protective element acting as a mobile base for the distributing v hopper, the lower part of which hopper rests on said base.

This device allows the distributing hopper to rotate in relation to the shaft furnace, quite independently of the two bells.

thus simplifying the design of the various sealing joints.

The seal around the hopper, the gastightness of which was difiicult to maintain in known arrangements because of stresses resulting inter alia from rotation of the hopper, is no longer so important a part of the hermetic seal as it was in the conventional charging device; it only operates when the small bell is lowered, which means that if necessary this seal could even be eliminated. The seal against which the small bell rests in the raised position is no longer subject to the same degree of wear from the dropping charge, or friction between the moving hopper and the small bell rotating therewith. Finally, the

reduced and the weighting of the rotational device can be eliminated. In fact, the pressure exerted-on the lower face of the small bell is now taken by fixed furnace framework which can readily be designed to withstand that thrust.

' According to another feature of the invention, the weight of I the hopper can be compensated by adjustable counterweights Difficulties in eliminating wear. and in dismantling and replacing joints are-additional drawbacks of the conventional charging systems.

Finally, in view of the high pressure acting on the lower face of the small bell when the large bell is lowered and the space between the two bells comes into communication with the furnace, it is essential to weight" the distributing hopper to prevent undue lifting of the hopper. It is impractical to make the rotating elements of the hopper alone withstand the total thrust to which the hopper is subjected through the small bell,

which thrust may amount to more than 80 tons depending on the dimensions of the bell and the'pressure in the furnace.

Apart from the space taken up by the ballast, there is the need to provide rotating elements for the hopper that are able to withstand the additional load.

' SUMMARY OF THE INVENTION An object of the present invention is to provide a charging device for a furnace enablingthe above drawbacks to be minimized and enabling the required gastightness between the furnace and the outside atmosphere through the various parts of the chargingdevice to be achieved simply and economically.

Although maximum economic advantage is obtained with the device according to the invention whena new plant is erected (because of weight reductions it permits), one advantage of the device is that it can be installed on existing blast so that the small hell can rise easily.

According to a further feature of the invention, the base on which the distributing hopper rests is suspended from an element adapted to move with the small bell, so that by lowering the small bell sufficiently (i.e. more than the sliding length of the hopper), the lower part of the hopper can be opened and the charge dumped into the space between the two bells, with a single actuating mechanism.

Yet a further feature of the invention is a protective element forthe small bell of cone-shape and tapering upwards to provide good distribution of the charge towards the large bell.

lt is also considered advantageous to give the protective element of the small bell a maximum radial dimension less than the maximum radial dimension of that of the small bell and to design the. longitudinal profile of the element so that the trajectory of the charge when sliding down the protective element is directed away from and does not meet the outside edge of the small bell. In designing this profile the lower part of the protective cone may be provided with a deflector by outwardly flaring the lower end of the protective cone proper.

This deflector enables the charge in the distributing hopper to be dumped on the large bell without touching the small bell and hence without any wear on the latter. The wear is transferred to the element acting as the mobile hopper bottom,

which can be repaired or replaced at low cost, as can the lower part of the hopper itself if necessary.

Although. it is not essential, it has also been found advantageous to provide the distributing hopper with a circular seal, on the one hand supported so as to be gastight on and all around the said hopper and, on the other hand fixed to the framework. In addition, an orifice is provided between this circular seal and a stop-seal of the bell to let out to recuperators, the small amount of gas escaping at the sides of the small bell whenever it is lowered to dump materials on the large bell, which is closed at that point. These last two arrangements are directed towards ensuring that the device is gastight towards the outside atmosphere throughout its operating cycle.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example only with reference to the accompanying drawings in which FIG. 1 is a vertical section through a furnace charging device, and FIG. 2 is an enlarged section of a part of the device shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION In the drawings a hopper 1 is the receiving hopper into which the skip or other charging means (not shown) delivers the materials to be put into the furnace, i.e. ore, flux and coke. The hopper 1, coaxial with a suspension device 2, dumps its charge into a hopper 3 known as the distributing hopper. TI-Ie hopper 3 has a guiding device allowing it a vertical movement by means of rollers fixed to the hopper and which can move on slide bars 4 supported on the furnace framework 5 under the control of a counterweight device. These slide bars are arranged at two levels around the hopper 3. The framework 5 supporting the hopper 3 can rotate about the longitudinalaxis of the furnace by means of a series of conical rollers 7 with radial axes regularly distributed around the hopper 3 but integral with a guide fixed to an airlock cone 6. The framework 5 rests on the said rollers by means of a raceway 21 provided at the top with a crown gear 22 on a vertical axis, coaxial with the hopper 3 and controlled by a toothed pinion 23 on a vertical axis. The vertical travel of the hopper is limited by stops 8 and 8a integral with the framework 5 on opposite sides thereof.

Thus suspended, the hopper 3, which has a slightly tapering upper part and a cylindrical lower part, rests by its own weight on a conical base 9 tapering upwards and acting as a protective cone for a small bell 10. The protective cone is suspended by a ball joint from a collar 11, the end ofa tube acting as the suspension rod for the cone. This rod is suspended by clamps and a thrust block from a bracket 12 integral with a hollow sleeve 13 to the end ofwhich is fixed the collar 11. The bell is itself suspended from this collar by means of a ball joint 14. The lower end of the cone 9 is slightly outwardly flared, at 90 as shown in FIG. 2, and its radial dimension is slightly less than that of the small bell. The periphery of the bell, in the raised position, is pressed against a seat formed by an annular seal 15 fixed to the framework. Above the said seal and also integral with the framework a pipe 16 allows gas to escape to recuperators (not shown). A circular gas tight seal 17 supported on the framework 5 (through the pipe 16) allows the hopper 3 to slide vertically while preventing gas passing from the inside to the outside and vice versa.

A large bell 18 is suspended by a shackle and pin from a connecting collar 19 fixed to the end of the suspension rod for the large bell. This rod is in the axis of the furnace and it passes through the hollow sleeve 13, in which it can slide by means of a gastight seal 20.

Thus constructed, the device according to the invention operates as follows:

Assume that the hopper of the large bell is full. To lower the large bell 18, the chamber formed by this large bell, the small bell 10, the airlock cone 6 and the hopper of the large bell must be brought to a pressure at least equal to that in the shaft, which is done by a pipe bringing gas under pressure into the said chamber. While the chamber is pressurized the bell 10 is held on its seat 15 by the pressure force itself, which ensures that the top of the chamber is gastight. Once the pressure is equalized on both sides of the large bell 18 the bell can drop and release the charge contained in its hopper. When the hopper is empty, the large bell can rise again and is held against its own seat by means of the pressure in the shaft.

When the large bell has risen again, the hopper immediately above it must be filled with the charge which has meanwhile collected in the hopper 3. A good distribution of the charge has already been ensured by rotating the hopper around its vertical axis, the hopper being supported in particular by the raceway 21 and its movement being controlled by the toothed pinion 23 driving the crown gear 22 integral with the raceway.

The next operation comprises the lowering of the hollow sleeve 13 supporting the small bell. In this movement the rod and cone 9 integral with the bell 10 are also lowered. The hopper follows the same movement solely'because it is resting by gravity on the cone 9. The three parts 10, 9 and 3 move down simultaneously until the lower part of the hopper 3 comes below the level of the seal 15. At this moment the balancing device of the hopper 3 presses on its stop 8 and halts the hopperwhile the small bell and cone 9 continue their descending movement, releasing the charge in the hopper. This charge cannot reach and wear the seal 15 which is screened by the wall of the hopper, nor can it reach and wear the outer edge of the small bell because of the flared terminal portion 9a of the cone 9 which acts as a deflector. During the movement of the charge, any compressed gases in the chamber between the two bells can escape through the pipe 16. The seal 17 prevents these gases and any dust they contain from escaping into the atmosphere.

The hopper 3, once emptied, can be raised without difficulty or strain since its weight is balanced by the counterweight. The small bell is also raised without any special effort. The correct centering of the small bell on the seal 15 and of the cone 9 on the base of the hopper is done automatically and independently by means of the ball joint 14. Once the complete device is back in place, the cycle can start again.

The device according to the invention enables the vertical movement of the distributing hopper to be controlled independently ofthe movement of the small bell. In addition, the seals, bells and other parts making up the furnace top are in a single piece and can be put in place by dismantling the rod of the large bell within the airlock at the connecting collar 19. Finally, the distributing hopper can be given a continuous or discontinuous rotating movement as desired.

We claim:

1. A charging device for a shaft furnace comprising, a framework a distributing hopper for receiving a furnace charge through charging means, a large bell, a small bell. means suspending said bells with the small bell above the large bell, means defining a chamber between the two bells, the distributing hopper being provided with a device enabling the hopper to slide along its longitudinal axis and with a rotating device, the small bell being provided with a protective element acting as a mobile base for the distributing hopper, the lower part of said hopper resting on said base said protective element having lower terminal edges, a gastight annular seal integral with the framework and arranged at least partially between the-lower terminal edges of the protective element and the small bell, with the small bell, in the raised position pressing against the annular seal, and the sliding device for the distributing hopper having a stop preventing downward movement of the hopper after the lower part of the hopper has reached and is screening the annular seal of the small bell.

2. The device as claimed in claim 1 in which the distributing hopper is provided with a counterweight device.

3. The device as claimed in claim 1, in which the base on which the distributing hopper rests is suspended from an element, adapted to move integrally with the small bell.

4. The device as claimed in claim 1, in which the protective element for the small bell is cone-shaped tapering upwards and its maximum radial dimension is less than the maximum radial dimension of the small bell.

5. The device as claimed in claim 1, in which the longitudinal profile of the protective element is designed so that in operation the trajectory of the charge does not meet the outside edge of the small bell.

6. The device as claimed in claim 5, in which the lower part of the protective element is flared outwardly to provide a charge deflector.

7. The device as claimed in claim l in which a cylindrical between the bells is provided with an orifice to allow escape of part of the distributing hopper is surrounded by a gastight seal gases to recuperators, the said orifice being situated between in which it moves vertically, the said seal also being integral the level of said seal and that of the annular seal of the small with the furnace framework, and in which the chamber bell. Y

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1. A charging device for a shaft furnace comprising, a framework a distributing hopper for receiving a furnace charge through charging means, a large bell, a small bell, means suspending said bells with the small bell above the large bell, means defining a chamber between the two bells, the distributing Hopper being provided with a device enabling the hopper to slide along its longitudinal axis and with a rotating device, the small bell being provided with a protective element acting as a mobile base for the distributing hopper, the lower part of said hopper resting on said base said protective element having lower terminal edges, a gastight annular seal integral with the framework and arranged at least partially between the lower terminal edges of the protective element and the small bell, with the small bell, in the raised position pressing against the annular seal, and the sliding device for the distributing hopper having a stop preventing downward movement of the hopper after the lower part of the hopper has reached and is screening the annular seal of the small bell.
 2. The device as claimed in claim 1 in which the distributing hopper is provided with a counterweight device.
 3. The device as claimed in claim 1, in which the base on which the distributing hopper rests is suspended from an element, adapted to move integrally with the small bell.
 4. The device as claimed in claim 1, in which the protective element for the small bell is cone-shaped tapering upwards and its maximum radial dimension is less than the maximum radial dimension of the small bell.
 5. The device as claimed in claim 1, in which the longitudinal profile of the protective element is designed so that in operation the trajectory of the charge does not meet the outside edge of the small bell.
 6. The device as claimed in claim 5, in which the lower part of the protective element is flared outwardly to provide a charge deflector.
 7. The device as claimed in claim 1 in which a cylindrical part of the distributing hopper is surrounded by a gastight seal in which it moves vertically, the said seal also being integral with the furnace framework, and in which the chamber between the bells is provided with an orifice to allow escape of gases to recuperators, the said orifice being situated between the level of said seal and that of the annular seal of the small bell. 